1. Technical Field of the Invention
The present invention relates generally to an easy-to-construct structure of an integrated control system for automotive vehicles which is designed to control a plurality of controlled elements such as an engine and an automatic transmission installed in a vehicle.
2. Background Art
U.S. Pat. No. 5,351,776 to Keller et al. teaches an automotive control system which works to control a plurality of controlled elements installed in the vehicle and is designed to have a structure easy to develop for a decreased period of time.
The control system defines the controlled elements such as an engine power control, a transmission control, a braking control, and a steering control arranged in a plurality of hierarchial levels and provides controlled performance required from the higher hierarchial level. The classification of the controlled elements into the hierarchial levels results in a decrease in number of the controlled elements to be changed in design when the specification of the system is to be changed, thus decreasing the time required for the change in system specification and permitting some of the controlled elements to be developed in parallel within decreased terms.
The control system, however, has a drawback in that the controlled elements should be so designed as to handle common controlled variables, which requires all the controlled elements to be redesigned.
Usually, control tasks to be carried out in typical engine control and transmission control systems are designed for every vehicle. Controlled variables used in carrying out the control tasks are also set for every vehicle. Thus, in a case where typical engine power control and transmission control devices are defined as the controlled elements of lower hierarchial levels in construction of the above control system, it may become impossible to operate the engine power control and transmission control devices using commands issued from the controlled elements of higher hierarchial levels. It, thus, becomes necessary to redesign the control tasks to be executed in the engine power control and transmission control devices or to change controlled variables to be used in the control tasks.
It is therefore a principal object of the invention to avoid the disadvantages of the prior art.
It is another object of the invention to provide an integrated control system for a vehicle which is easy to construct without redesigning control tasks to be executed in typical controlled elements and/or changing controlled variables to be used in the control tasks.
According to one aspect of the invention, there is provided an integrated control system for a vehicle designed to have a structure which is easy to construct without redesigning a plurality of controlled elements such as components of a power train of the vehicle. The control system comprises: (a) a manager circuit providing a plurality of target values of given controlled variables; (b) a plurality of control circuits designed to perform given control tasks of controlling operations of a plurality of controlled elements installed in the vehicle for bringing the controlled variables into agreement with the target values provided by the manager circuit; and (c) a translating circuit translating the target value of at least one of the controlled variables into a target value of a second controlled variable which is predefined as being used in performing at least one of the control tasks in the control circuits to bring the one of the controlled variables into agreement with the target value.
In the preferred mode of the invention, a condition comparing means is further provided which compares a given controlled variable-related condition associated with the controlled element which is controlled in operation using the second controlled variable with a reference controlled variable-related condition to determine a difference therebetween. A translation correcting means is provided which corrects a translation scheme of the translating circuit so as to compensate for an error between the target value of the one of the controlled variables and an actual one arising from the difference between the controlled variable-related condition and the reference controlled variable-related condition.
A correcting means may alternatively be provided which corrects the target value of the one of the controlled variables so as to compensate for an error between the target value and an actual one arising from the difference between the controlled variable-related condition and the reference controlled variable-related condition.
At least one of the control circuits may alternatively produce a target value of a third controlled variable as a control request to another of the controlled circuits which is different from the controlled variable provided by the manager circuit to the another of the control circuits. A controlled variable translating circuit is provided which is designed to translate the target value of the third controlled variable into a target value of the controlled variable provided by the manager circuit to the another of the control circuits.
The translating circuit translates the target value of the controlled variable provided by the manager circuit to the another of the control circuits plus the target value translated by the control variable translating circuit into a target value of the second controlled variable which is predefined as being used in performing the control task in the another of the control circuits.
The control circuits may be designed to control operations of controlled elements of a power trains of the vehicle including an engine. The manager circuit determines the target values of the controlled variables so that a drive force of the vehicle reaches a target one. The translating circuit translates the target value of the controlled variable into the target value of the second controlled variable as a function of speed of the engine.
One of the control circuits designed to control the engine may be an engine control circuit. In this case, at least one of the control circuits except the engine control circuit provides a control request signal indicative of a target retard ignition angle to the engine control circuit. The controlled variable translating circuit is designed to translate the target retard ignition angle into a target value of the controlled variable provided by the manager circuit to the engine control circuit. The translating circuit adds the target value of the controlled variable provided by the manager circuit to the engine control circuit to the target value translated by the controlled variable translating circuit to provide an ultimate target value of the controlled variable to the engine control circuit.
The manager circuit may provide a controlled parameter indicative of either of a target engine torque and a target engine output power as the target value of the controlled variables to the engine control circuit. The translating circuit translates the controlled parameter into a second controlled parameter indicative of a target position of a throttle valve of the engine. The engine control circuit performs a throttle control task to actuate the throttle valve so that the target position of the throttle valve is reached.
The translating circuit works to translate the controlled parameter into the second controlled parameter based on a response characteristic of the engine to a change in position of the throttle valve for compensating for a response lag between a change in engine torque and a change in position of the throttle valve.
At least one of the control circuits except the engine control circuit may provide a control request signal indicative of a target retard ignition angle to the engine control circuit. In this case the controlled variable translating circuit is designed to translate the target retard ignition angle into a correction parameter which indicates an amount of engine torque or engine output power to be changed and is equivalent in kind to the controlled variable provided by the manager circuit to the engine control circuit. The translating circuit corrects the controlled parameter indicative of either of the target engine torque and the target engine output power using the correction parameter and uses the corrected controlled parameter to produce the second controlled parameter indicative of the target position of the throttle valve of the engine.
The engine control circuit may also be designed to perform an ignition timing control task of retarding ignition timing of the engine. In this case, the translating circuit produces the second controlled parameter indicative of the target position of the throttle valve in a range within which as much of either of the target engine torque and the target engine output power as possible is reached and also translates a lack of either of the target engine torque and the target engine output power which is not achieved by control of the throttle valve into a target retard ignition angle achieved by performing the ignition timing control task in the engine control circuit.
A condition comparing means may further be provided which compares a given operating condition of the engine with a pre-defined reference operating condition of the engine to determine a difference therebetween. The translation correcting means may be designed which corrects the translation scheme of the translating circuit so as to compensate for an error between the target value of the one of the controlled variables and an actual one arising from the difference between the given operating condition and the pre-defined reference operating condition.
A correcting means may be provided which corrects the target value of the one of the controlled variables so as to compensate for an error between the target value and an actual one arising from a difference between the given operating condition and the pre-defined reference operating condition.
The difference as determined by the condition comparing means is at least one of (a) a difference between an actual ignition timing of the engine and a pre-defined reference ignition timing of the engine, (2) a difference between an actual atmospheric pressure and a pre-defined reference atmospheric pressure, (3) a difference between an actual boost pressure of a turbocharger installed in the engine and a pre-defined reference boost pressure of the turbocharger, (4) a difference between an actual opening timing of intake and exhaust valves of the engine and a pre-defined reference opening timing of the intake and exhaust valves, (5) a difference between an actual amount of lift of intake and exhaust valves of the engine and a pre-defined reference amount of lift of the intake and exhaust valves, (6) a difference between an actual amount of exhaust gas recirculated through an exhaust gas recirculation system and a pre-defined reference amount of recirculated exhaust gas, (7) a difference between an air-fuel ratio of a mixture supplied to the engine and a pre-defined reference air-fuel ratio of the engine, (8) a difference between a load exerted on the engine produced by an auxiliary mechanism driven by the engine and a pre-defined reference load, and (9) a difference between an actual output torque of the engine and a pre-defined reference output torque of the engine.
The power train may include an automatic transmission with a torque converter. In this case, the actual output torque may be determined based on a speed of the engine and a speed of an output shaft of the torque converter.